Packaging system

ABSTRACT

High speed case and carton sealing lines for packaging articles. The carton to be packaged, i.e., filled and sealed, having disposed thereon an adhesive comprising an energy-absorbing ingredient that is capable of absorbing and reflecting radiant energy. The automated packaging machine comprises a means to reactivate an adhesive to effect sealing.

FIELD OF THE INVENTION

[0001] The invention relates to a packaging system, and moreparticularly to a packaging machine. The packaging machine is adapted toactivate an adhesive applied to a carton blank prior to use by thepackager in a packaging machine.

BACKGROUND OF THE INVENTION

[0002] Adhesives are widely used for various commercial applications.Hot melt adhesives, for example, are commonly used in product assemblyand packaging applications, including cardboard case sealing and cartonclosing operations. Such hot melt adhesives are applied to a substratewhile in its molten state and cooled to harden the adhesive layer.

[0003] In the conventional case and carton packaging process for foodand consumer goods, the boxes are first filled with food or consumergoods, then a hot melt adhesive is applied to the flap of boxes on thepackaging line and compression is exerted to seal the boxes. While thisprocess works reasonably well, it requires the packaging company todevote a tremendous amount of time and attention to adhesive-relatedissues, including adhesive selection, processing, trouble-shooting,inventory, and maintenance of adhesive application equipment. First,selection of an adhesive having the required adhesion, setting speed,and open time is a lengthy process. Then the adhesive needs to beprocessed in an appropriate way such as melting, transporting, andapplying. If anything is wrong with the processing, the boxes will notseal properly, the packaging line must be stopped, and the problemidentified and fixed.

[0004] Re-activation or heat sealing of pre-applied adhesives is knownand practiced in the art. Heat sealed closures and seams are commonlyused in the manufacture of bags, whereby adhesive is coated on theinside of the bag seam and subsequently sandwiched under intense heatand pressure using heated platens or bars. This direct application ofheat and pressure renders the adhesive molten, after which a bond isformed. This application benefits from the ability to apply steadydirect pressure to ensure intimate contact and sufficient wetting of theadhesive layer to the substrate. This process cannot be used forapplications where high pressure for closing is not available, such asin case and carton packaging processes. While focused hot air has beenused in the reactivation of pre-applied adhesives used in case andcarton sealing operations, this method requires extremely large amountsof energy and can result in undesired heating of the substrate orpackage, its contents, and the surrounding area and equipment. Moreover,line speed is slow.

[0005] A need exists in the art for a packaging system that canadvantageously be used for case and carton sealing whereby the case orcarton to be formed, filled and sealed is provided to the packager withadhesive already applied to the case or carton and later, duringpackaging, reactivated in order to close or seal the case or carton. Thecurrent invention addresses this need.

SUMMARY OF THE INVENTION

[0006] The invention provides a packaging machine adapted to reactivatean adhesive or sealant composition that has been previously applied tothe case or carton.

[0007] One aspect of the invention is directed to a packaging machineadapted to activate an adhesive applied to a substrate by the packagemanufacturer, also referred to as the converter. Form, fill and sealpackaging machines In a preferred embodiment the adhesive is activatedupon exposure to short durations of radiant energy.

[0008] The packaging machine comprises a frame, a plurality of stationscarried by the frame and a drive assembly. A conveying assembly isoperably connected to the drive assembly for moving the cartons throughthe stations. Stations include a carton erection station, a fillingstation and a means for reactivating an adhesive present on at least aportion of a carton. Many packaging machines will also comprise a bottomflap sealing station and/or a top flap sealing station. If both bottomand top flaps are to be sealed, they may be sealed simultaneously or,alternatively, sequentially.

[0009] Another aspect of the invention relates to carton blanksincluding flat, folded carton blanks having applied on at least onesubstrate surface thereof an adhesive capable of being activated uponexposure to short durations of radiant energy. The adhesive applied tothe case or carton comprises an effective amount of an energy-absorbingingredient such that upon exposure of the adhesive to radiant energy,the adhesive is activated. The energy-absorbing ingredient selected foruse may be dissolved and/or dispersed within the adhesive composition.Organic dyes and pigments are particularly useful energy-absorbingingredients for use in the practice of the invention. Adhesivescomprising carbon black and NIR absorbing dyes are particularlypreferred for use in the practice of the invention. Upon exposure toradiant energy, the adhesive melts to the extent that it is capable ofbonding the substrate surface to a second substrate surface.

[0010] Still another aspect of the invention is directed to an automatedprocess for packaging a consumer good by forming, filling and,optionally sealing a container (e.g., a case or carton) that has hadapplied to at least a portion thereof a reactivatable adhesivecomprising an energy-absorbing ingredient.

[0011] In preferred embodiments the adhesive is present on at least onetop and/or at least one bottom flap. The method comprises obtaining aflat folded carton blank comprising an adhesive containing an energyabsorbing ingredient, erecting or forming a tubular shaped packagingcapsule, placing an object to be packaged in the tubular packagingcapsule, irradiating the applied adhesive with radiant energy for a timesufficient to melt the adhesive, bringing one substrate (e.g., a firsttop or bottom flap) in contact with the melted adhesive on anothersubstrate (e.g., a second top or bottom flap), and allowing the adhesiveto solidify thereby bonding the first substrate (flap) to the secondsubstrate (flap) and sealing the container. Optionally, pressure mayalso be applied to effect said closing. If the substrate is transparentor translucent to the energy used for reactivation, the container may beclosed and then NIR energy can be applied to initiate cure.

[0012] In other embodiments, a container is formed by folding apackaging blank along pre-predetermined fold lines, reactivatingadhesive present on predetermined areas of the packaging blank andsealing at least one portion of the packaging blank to a second portionof the packaging thereby forming the container. The article to bepackaged may be inserted into the package either during the formation ofthe package, such as in conventional wrap-around packaging, or after,such as in conventional Bliss box packaging, tray formation, in themanufacture of boxes and bags.

[0013] Yet another aspect of the invention is directed to an automatedprocess for packaging a consumer good by forming, filling and sealing acontainer (e.g., a case or carton) that has had applied to at least aportion thereof a reactivatable adhesive comprising an energy-absorbingingredient. In preferred embodiments the adhesive is present on at leastone top and at least one bottom flap. The method comprises irradiatingthe applied adhesive with radiant energy for a time sufficient to meltthe adhesive, bringing one substrate (e.g., a first top or bottom flap)in contact with the melted adhesive on another substrate (e.g., a secondtop or bottom flap), and allowing the adhesive to solidify therebybonding the first substrate (flap) to the second substrate (flap) andsealing the container. Optionally, pressure may also be applied toeffect said closing. In the practice of the invention, exposure toradiant energy is typically for periods of less than about 5 seconds,more typically for a period of less than about 3 seconds. Pressure istypically applied for periods of less than about 30 seconds, moretypically less than about 5 seconds. If the substrate is transparent ortranslucent to the energy used for reactivation, the adhesive formulamay be sandwiched between substrates first, and then NIR energy can beapplied to initiate cure.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0014] Drawing FIGS. 1-4 illustrate several types of packaging havingadhesive pre-applied to the substrate surface thereof.

[0015]FIGS. 1 and 2 illustrate typical form, fill and seal embodimentsof the invention.

[0016]FIG. 3 illustrates a typical Bliss box package.

[0017]FIG. 4 illustrates a typical wrap around package.

DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention is directed to a packaging system. Thepackaging system comprises a machine adapted for reactivation of anadhesive applied during the manufacture of a packaging substrate (e.g. acontinuous web), a packaging blank (e.g., a carton blank), or the likecomprising a reactivatable adhesive. Alternatively, the adhesive may beapplied following the manufacture of the packaging blank but prior touse of the carton blank in the packaging of an article, e.g., a consumergood.

[0019] The packaging system provides an improvement over prior artpackaging systems that require application of adhesive to a packagingblank at one or more gluing stations located within the packagingmachine.

[0020] Packages or containers are used interchangeably herein andinclude cartons, cases, trays, bags, boxes and the like. I.e., anythingused to package a consumer goods such as food and beverages,pharmaceuticals, cosmetics, breakfast cereals, beverage containers(e.g., beer bottles and the like), bakery items, dry foods (e.g., dogfood), produce, household products, paper products, soaps anddetergents, candy, wet food, frozen food, diapers and the like, and hardgoods such as but not limited to tools, fasteners, automotive parts, andlight bulbs.

[0021] While the term case is generally used in the art to refer toouter shipping containers typically made of corrugated paperboard andthe term carton is generally used in the art to referr to a containertypically manufactured from solid fiber (e.g., a cereal box), theinvention will hereinafter refer generally to the manufacture of a“carton.” It is to be understood however that the invention is not to beso limited.

[0022] Reactivation, as this term is used herein, refers to an adhesivethat resides on at least a portion of at least one substrate to bebonded. In the context of a hot melt adhesive, the adhesive has beenapplied to a substrate in the molten state and allowed to cool, i.e.,solidify, thereon. The adhesive present on the substrate is thereafterreactivated or heated to a molten state, brought in contact with asecond substrate and allowed to cool or solidify, thereby bonding thetwo substrates together. The application of the adhesive onto asubstrate for later activation or “reactivation” is referred to herein,and in the art as a “pre-applied” adhesive.

[0023] The reactivation efficiency of an adhesive refers to the abilityof the adhesive to reactive, e.g., become molten in a short period oftime. Reactivation efficiency will depend on the power of the device andthe distance of the energy source from the adhesive. Reactivation timedepends on receptivity of the adhesive, which depends on the energyabsorbing ingredient, the coating weight or thickness of the adhesiveand the energy flux density that the radiant source can supply to theadhesive (e.g., intensity per unit area). Energy flux density refers tothe distance, focal point, power and intensity of the lamp or powersource.

[0024] Preferably, the reactivatable adhesives are formulated toreactivate to a temperature of at least about 200° F., more preferablyto a temperature of at least about 250° F. upon exposure of less thanabout 1200 watts/sq inch of near infrared energy for a period of lessthat about 10 seconds, more preferably less than about 5 seconds, evenmore preferably less than about 3 seconds.

[0025] The adhesive compositions applied to the packaging substratecontains an energy absorbing ingredient that increases the absorptionand reduces the transmission of radiant energy that creates atemperature distribution within the adhesive that optimizes performance.The adhesives have improved re-activation and performance propertiesafter irradiation. The adhesives of the invention reactivate on exposureto short durations of radiant energy and provide superior on-lineperformance and set speed that allows for quicker production speeds.

[0026] The improved re-activation and performance may preferable beachieved by incorporating into an adhesive an energy-absorbingingredient. Energy-absorbing ingredients include those dyes, pigments,fillers, polymers and resins other ingredients that are capable ofabsorbing energy and provide an optimal balance of absorption,reflection, transmission and conduction.

[0027] It has been discovered that when a suitable energy-absorbingingredient is added to a conventional adhesive, reactivation upon shortduration of radiant energy can be achieved. Energy-absorbing ingredientscontemplated for use in the practice of the invention are commerciallyavailable and include, but are not limited to dyes, pigments andfillers. Examples include carbon black, graphite, Solvent Red(2′,3-dimethyl-4-(2-hydroxy-naphthylazo)azobenzene), Solvent Green, dyessuch as Forest Green and Royal Blue masterbatch dye available fromClariant, cyanine-based dyes, oxides such as such as titanium dioxide,and metals such as antimony, tetrakis)dialkylaminophenyl)aminium dyes,cyanine dyes, squarylium dyes and the like.

[0028] Pigments, such as carbon black and graphite, are particulate innature and will usually have somewhat of a spherical shape with averageparticle sizes in the range of about 0.01 to about 7 microns. Pigmentparticles aggregate, so aggregate size will be larger. The pigmentaggregate size in hot melt adhesives will preferably be smaller thanabout 500 microns. Aggregate sizes of less than about 100 microns arepreferred, more preferably smaller than about 50 microns.

[0029] A wide variety of organic NIR triggers are described in theliterature and are available for use in the practice of the invention.Such compounds include cyanine, metal complexes, quinone, azo, radicalmultiphenylmethane, perylene, aromatic annulenes, fluorenylium. Suchtriggers possess various absorption characteristics. For example,halogen substituted 1,4,5,8-tetraanilioanthraquinones have excellenttransmittance in the vicinity of 860 nm and can absorb NIR in otherranges. Another example is squaraine, which is characterized by intensenarrow absorption bands at relatively long wavelength. Also specificallydesigned phthalocyanine compounds have been demonstrated exhibiting hightransmittance to visible light and offering high efficient cut of nearinfrared.

[0030] Preferred energy-absorbing ingredients for use in the practice ofthe invention are broad band near IR absorbers such as Epolight 1125(Epolene, Inc), SDA6248 (H.W. Sands Corp.), SDA2072 (H.W. Sands Corp.)and carbon black. Carbon black can be purchased from Cabot under tradename of Monarch, Regal, Black Pearl, and Elftex, or Degussa (FW series),or from Columbian Chemical Company (Raven Series). Carbon black can bemanufactured by different methods such as the furnace black method, thegas (channel) black method, and the lamp black method. The keyparameters affecting the radian energy absorption of carbon blackprepared by these various methods are average primary particle size,surface chemistry and aggregate structure.

[0031] Energy absorbing ingredients for use in the practice of theinvention will typically have an absorption in the range of from about400 nm to about 100,000 nM, more preferably from about 700 nm to about10,000 nm, even more preferably from about 750 nm to about 5000 nm.

[0032] Suitable energy-absorbing ingredients for use in reactivatableadhesives of the invention may be identified by blending a desiredadhesive with a chosen additive of various particle size and variousamounts. Any conventional method of blending the energy-absorbingingredient with the adhesive such as through use of a paddle mixer orhigh shear mixer such as Ross ME-100LC extruder, as would be apparent tothe skilled practitioner, may be used to prepare the adhesivecompositions of the invention. The starting adhesive and the adhesivecontaining the energy-absorbing ingredient then are compared by heatingsamples of each with a light from a radiant heat source. The samples aretested for reactivation efficiency and bonding performance, as describedin detailed in the Examples. Reactivation efficiency is the ability theadhesive to become molten in a short period of time. Suitable additivesare those that reactivate quickly and exhibit acceptable bond strength.Preferred are thermoplastic adhesives which, when pre-applied to asubstrate, re-activates with a short duration of exposure to radiantenergy, preferably less that about 10 seconds, more preferably less thanabout 5 seconds, and provides acceptable bond force after a short periodof compression or cooling, preferably a period of less that about 30seconds, more preferably less than about 15 seconds.

[0033] Included in the practice of the invention are adhesivescomprising absorber coated fillers and encapsulated absorbers. Forexample, the adhesive may comprise a cureative encapsulated within ashell comprising a NIR absorbing agent. Exposure to NIR energy melts thecapsule thereby expelling the curing agent and allowing for cure of theadhesive.

[0034] The term tubular, as in a tubular package or tubular packagingcapsule is not limited to a cylindrical shaped package but encompassesrectangular shaped packages as well as triangular, hexagonal,pentagonal, octagonal and the like shaped packaging. Packagingcontainers can have a rectangular, circular, square or other shapedcross-section.

[0035] Paperboard-based containers are in widespread use for thepackaging of consumer goods. A typical rectangular packaging containercomprises a pair of vertical side panels and a pair of top and bottompanels contiguous with a respective one of the vertical side panels.

[0036] Adhesive is used in all areas of packaging technology (convertingand packaging) for the purpose of sealing paper-based containers, e.g.,for connecting or sealing folding tabs such as the side seam and top andbottom end flaps.

[0037] In the paper converting process, laminated paperboard cartons arecut to the desired shape for the carton blank, and the fold or creaselines are formed in the laminated structure by a process much likeembossing. Subsequent to the converting process, the only fold or creaselines that are further manipulated are those necessary to form the flat,folded configuration. As will be recognized by those skilled in the art,in this configuration, a first and second panel and a third and fourthpanel are folded over their respective shared fold or crease lines sothat the side seal for the carton (at the fifth panel or flap) can bemade. The side seal is conventionally made by the converter. This flatfolded configuration is that configuration in which the cartons aresupplied to the packagers. All subsequent folds and seals are carriedout as part of the packaging machine operation.

[0038] Conventional packaging machines includes a carton magazine forstoring flat, folded carton blanks, a feeder for advancing carton blanksto be filed, a carton erection station, a bottom forming and sealingstation, and a filling station at which the cartons are filled withproduct. Following the filling station the cartons' top panels arefolded and subsequently sealed. The filled cartons are then off-loadedfrom the form, fill and seal packaging machine.

[0039] It is evident that prior art packaging machines require at leastone gluing station, and usually two, requiring the packager to deal withadhesive inventory, trouble shooting, maintenance of adhesiveapplication equipment and the like.

[0040] As described in commonly assigned and concurrently filedapplication Ser. Nos. ______ ______ (ATTY docket Nos. 2088 and 2089),both entitled “Method and means for pre-applying an adhesive to asubstrate,” the disclosure of which is incorporated herein in itsentirety by reference, the converter, in addition to forming the sideseal, applies to at least one predetermined location an amount ofadhesive sufficient to seal the container. The adhesive applied to thecarton blank comprises an energy-absorbing ingredient. By including anenergy-absorbing ingredient, the absorption, reflection and transmissioncharacteristics of the adhesive composition is tailored so as tooptimize the composition's re-activation and subsequent bond formation.The adhesive is applied to the substrate and, depending on the type ofadhesive applied, allowed to dry or solidify. Such adhesives are capableof reactivating upon short duration of exposure to radiant energy,preferably less that about 10 seconds, more preferably less than about 5seconds, even more preferably less than about 3 seconds, and providesacceptable bond force after a short period of compression or cooling,preferably a period of less that about 30 seconds, more preferably lessthan about 15 seconds.

[0041] Thus, the flat folded configuration supplied to the packager hasall the adhesive elements required to seal the container and thepackager can avoid applying adhesive in the packaging line and avoid theproblems associated with such application.

[0042] The present invention provides a packaging machine adapted toactivate an adhesive present on a carton blank, i.e., a pre-appliedadhesive. The machine comprises at least one station capable ofproviding a directed source of energy to the adhesive present on thecarton blank.

[0043] Radiant energy can be supplied by a number of sources, as will beapparent to the skilled practitioner. Both coherent and non-coherentsources may be used. Examples include lasers, a high pressure xenon arclamp, a coiled tungsten wire, ceramic radiant heater, tungsten-halogenlamps and ultrasonic waves. In a preferred embodiment, radiant energywithin the near infra-red (NIR) region is used. Peak wavelengths of from400 nm to about 100,000 nm may be used. More typically, wavelengths offrom 700 nm to about 10,000 nm, most typically from about 750 nm toabout 5000 nm will be used in the practice of the invention. Commercialsources of equipment capably of generating radiant heat required for usein the practice of the invention include Research Inc. (Eden Prairie,Minn.), Chromalox (Ogden, Utah), DRI (Clearwater, Fla.), Advent ElectricInc. (Bridgeport, Pa.), and Glo-Quartz Inc. (Mentor, Ohio).

[0044] In the form, fill and seal packaging machine of the invention, aplurality of carton blanks having positioned thereon an adhesivetailored for purpose of reactivation are stored in a flat form in amagazine. The blanks are dispensed by a feeder to a carton formingstation where the cartons are erected, bottom sealed, filled and topsealed. In this process, the cartons can also be sterilized, forexample, after bottom sealing. The cartons are conveyed in an indexedmanner through the various stations and subsequently discharged from themachine at an off-loading station. Generally, the cartons are conveyedthrough the machine by a belt or like conveying device. The cartons willtypically be supported from their respective bottoms which will normallyrest on a low friction, stationary table top-like portion of the machineassociated with the conveyor.

[0045] The packaging machine of the invention comprises a magazine forstoring stacks of flat folded carton blanks, a carton erection station,a filling station and a top and/or bottom forming and sealing station atwhich will be located a means for proving radiant energy. It is to beunderstood that the terms “bottom” and “top” are relative terms and notterms used to designate the top or bottom of the finished packagedarticle. Located at each of the bottom and top sealing stations is ameans for proving radiant energy to the adhesive located onpredetermined area of the bottom and top forming flaps. The specificsource of energy and distance from the surface to be irradiated will bedictated by the type and amount of adhesive used. In one embodiment, theenergy source is NIR radiation. It is to be understood that theselection and duration of the radiant energy used will depend on theenergy absorbing material incorporated into the adhesive located on thecontainer being sealed.

[0046] In one embodiment, the packaging machine forms and seals one endof the carton, fills the carton and then forms and seals the other endof the carton. In such an embodiment the top and bottom of the cartonwill be sealed sequentially and the source of energy used to seal thebottom will be located at a site distal the source of energy used forsealing the top. In another embodiment of the invention, the packagingmachine fills the carton prior to sealing either end (i.e., the bottomand top ends) of the carton. In this embodiment, the top and bottom ofthe carton will be sealed substantially simultaneous to each other, withthe energy sources located substantially juxtapose to one another.

[0047] While the adhesive may be applied directly to the carton, theadhesive to be reactivated during the packaging of the carton may beplaced on the carton blank via a transfer tape or the like. Amongtransfer tapes contemplated for use is a tape comprising a backingmaterial having a first and a second opposing surface. On one surface isdisposed, for example, a pressure sensitive adhesive and on the secondsurface is disposed a reactivatable adhesive. Useful backing materialsubstrates include foam, metal, fabric and various polymer films such aspolypropylene, polyamide and polyester. The pressure sensitive adhesivebeing used to apply the reactivatable adhesive to the surface of thecarton prior to or during the packaging and sealing thereof.

[0048] In contrast to adhesives applied on the packaging line, it hasbeen discovered that adhesive reactivated in accordance with theinvention have improved performance properties. Moreover less adhesiveis required to be used when pre-applied than when applied on the line.Carton blanks used in the practice of the invention will typically becoated with from about 0.5 mil to about 15 mil of adhesive. The adhesivepresent on the carton blank reactivates upon exposure to short durationsof radiant energy and provide superior on-line performance and set speedwhich allows for quicker production speeds.

[0049] The type of adhesive that can be reactivated in accordance withthe invention is not particularly limiting or critical to the practiceof the invention. Reactivatable adhesives encompassed by the inventioninclude but are not limited to hot melt adhesives, waterborne adhesives,solvent borne adhesives, moisture curable adhesives, ultraviolet curableadhesives, blocked urethane systems, epoxy based adhesives, andadhesives comprising an encapsulated cureative or the like.Thermoplastic and hot melt adhesives are particularly useful whenformulated for pre-application and subsequent later reactivation and areparticularly useful for case and carton sealing. It will be apparentthat a thermoplastic adhesive present on a substrate may be applied to asubstrate in the form of a waterborne emulsion or solution.

[0050] Adhesives reactivateably by application of a NIR energy sourceand adhesives reactivatable by application of ultrasonic waves areparticularly preferred for use in the practice of the invention.

[0051] The energy-absorbing ingredient may be added, with stirring, anytime during the preparation of the base adhesive, or followingpreparation of the base adhesive. The amount added will depend on thetype adhesive, the energy-absorbing ingredient used, the size of theenergy-absorbing ingredient and the dissolution or dispersion propertiesof the energy-absorbing ingredient. The additive is added in an amounteffective to reactivate the adhesive upon exposure to short durations(typically less that 10 seconds) of radiant energy. Typically, theadditive will be present in an amount of about 0.001 to about 10 partsper 100 parts of the adhesive composition. Reactivatable adhesivescontaining an energy-absorbing ingredient are described in copendingcommonly assigned U.S. application Ser. No. 09/933,279, entitled“Reactivatable adhesives” and in commonly assigned and concurrentlyfiled application Ser. No. ______ (ATTY docket No. 2090), entitled“Reactivatable adhesive compositions and use thereof,” the disclosuresof which is incorporated herein in their entireties by reference.

[0052] In embodiment where the adhesive is sensitive to ultrasonic wavesand the invention involves bringing one substrate in contact with theadhesive present on a second substrate, subjecting the first and/orsecond substrate to ultrasonic compression for a time sufficient tomelt/reactivated the adhesive and allowing the adhesive to solidifywhereby the first substrate is bonded to the second substrate. Inembodiments were reactivation occurs by exposure to ultrasonic energy,the adhesive present on the first substrate may be reactivated eitherbefore or after being contacted with the second substrate to be bondedthereto.

[0053] The re-activation and performance of ultrasonically reactivatableadhesives is achieved by incorporating into an adhesive anenergy-absorbing ingredients that are sensitive to ultrasonic energy.Examples include thermoplastics, thermosets, low Tg polymers, compositesand blends thereof.

[0054] The reactivation efficiency of an adhesive refers to the abilityof the adhesive to reactive, e.g., become molten in a short period oftime. Reactivation efficiency will depend on the compression pressure,the power and frequency of the ultrasound, the geometry and contact areaof the ultrasonic horn and the exposure time.

[0055] Adhesives reactivatable by the application of ultrasonic wavesare described in commonly assigned and concurrently filed applicationSer. No. ______ (ATTY docket No. 2091), entitled “Reactivation ofpre-applied adhesives by ultrasonic waves,” the disclosure of which isincorporated herein in its entirety by reference.

[0056] Preferred formulations for the adhesive layer will comprisestyrene-butadiene-styrene copolymers, ethylene vinyl acetate, a wax anda tackifier. Elastomeric adhesives with glass transition temperaturesbelow 20 C, or semicrystalline polymers with a melting temperature ofbelow about 20C are particularly preferred.

[0057] Preferred reactivatable adhesive will reactivate upon exposure toultrasonic energy having a frequency of from about 15-kilohertz to about60 kilohertz, more preferably from about 20 kilohertz to about 40kilohertz. Preferably, the reactivatable adhesives are formulated toreactivate to a temperature of at least about 200° F., more preferablyto a temperature of at least about 250° F. upon exposure of less thanabout 2000 watts/sq inch of ultrasonic energy for a period of less thatabout 10 seconds, more preferably less than about 5 seconds, even morepreferably less than about 3 seconds.

[0058] Ultrasonic generators used in the practice of the inventiongenerally and conventionally comprise a transducer, a booster and horn.A booster is typically used to amplify and boost energy. Ultrasonichorns are known in the art and include rectangular horns and rotaryhorns of cylindrical shape. Preferred geometry for use in the practiceof the invention is to press the ultrasound horn onto substrate layerswhere the adhesive layer is sandwiched in the middle. Alternatively, thesubstrate may be pressed into the horn. The ultrasonic energy willtypically be used at a frequency of from about 15 kilohertz to about 60kilohertz, more preferably from about 20 kilohertz to about 40kilohertz.

[0059] The packaging machine of the invention is not limited to theclosure of paperboard containers. The packaging machine may be used toseal containers made of a variety of materials. Substrates to be bondedinclude virgin and recycled kraft, high and low density kraft, chipboardand various types of treated and coated kraft and chipboard. Compositematerials are also used for packaging applications such as for thepackaging of alcoholic beverages. These composite materials may includechipboard laminated to an aluminum foil which is further laminated tofilm materials such as polyethylene, mylar, polypropylene,polyvinylidene chloride, ethylene vinyl acetate and various other typesof films. Additionally, these film materials also may be bonded directlyto chipboard or kraft. The aforementioned substrates by no meansrepresent an exhaustive list, as a tremendous variety of substrates,especially composite materials, find utility in the packaging industry.

[0060] In addition to the advantantages of using a pre-applied adhesiveis case and carton sealing operations, use of a pre-applied adhesive inaccordance with the invention for the sealing of paper bag endings,pinch bottom bags and the like in place of conventional heat sealclosure has the advantage of expanding the types of graphics used inthese applications, as the heated compression conventionally used in theart limits the use thereof.

[0061] By modifying the placement of adhesive on the substrate (e.g.,top or bottom end flap, vertical side section), the size or surfacearea, the shape and/or pattern of the adhesive applied to the substrate,packaging may be designed to control the amount of force required toopen a sealed package, i.e., control the ease of opening. Thus packagingcan be designed that is child proof or, alternatively, geriatricallyfriendly (i.e., easy open). The adhesive formulations of the inventionmay be pre-applied in a continuous or discontinuous, e.g., as evenlyspaced beads or dots, manner depending on surface area and coatingweight desired. Particular patterns may be used to optimizesubstrate/adhesive contact. Depending on the adhesive, the bead size,thickness, distance apart and pattern will vary.

[0062] In addition, packaging substrates comprising a preappliedadhesive in accordance with the invention is cost effective and enablesthe use of many packaging designs that could not heretofore be used withprior art packaging systems. Adhesive may be placed and packagesdesigned to be tamper resistant/tamper evident. Specifically, problemsassociated with adhesive stringing and adhesive “ooze out” or “squeezeout” upon sealing/compression operations encounter in prior art packagesand packaging processes that apply glue on the line are avoided whenusing reactivatable adhesives. Using the process of the invention,packaging materials such as carton blanks can be manufactured that useless paperboard stock. As such, the reactivatable adhesives of theinvention may be precisely preapplied to the area to be sealed. The areaof adhesive application can be located closer to the distal portion ofan end flap to be sealed. This advantage means substantially savings inthe amount of packaging materials needed (i.e., the end flap may besmaller). The areas of adhesive may also be placed closer to the foldline, enabling the use of a lighter weight paperboard substrate stock,which also results in a substantial cost savings.

[0063] Drawing FIGS. 1-4 illustrate several types of packagingencompassed by the invention. FIGS. 1 and 2 illustrate typical form,fill and seal embodiments of the invention. FIG. 1A shows a flat cartonblank having reactivatable adhesive applied to the one flap of each setof end flaps. FIG. 1B shows the carton folded. FIG. 2 shows a flat form,fill and seal type carton having reactivatable adhesive applied tovarious end flap fold lines as well as flap sides. This box is designedto be sift proof and tamper proof. Sift proof boxes have an additionaladvantage that use of secondary packaging material (e.g., the bag withinthe cereal carton) can be avoided. FIG. 3 illustrates a typical Blissbox package. It will be appreciated that adhesive may, alternatively beplaced on'the two end panels. FIG. 4 illustrates a typical wrap aroundpackage. Many other packaging designs as will be apparent to one skilledin the art are encompassed by the invention.

[0064] The invention is further illustrated by the followingnon-limiting examples.

EXAMPLES Example 1

[0065] Adhesive Sample 1

[0066] An adhesive sample was prepared by blending an EVA, paraffin wax,and hydrocarbon tackifier based hot melt adhesive available fromNational Starch & Chemical Company (Cool-Lok® 34-2125) with 0.3 wt % ofcarbon black (Regal 400, Cabot) using a paddle mixer.

[0067] Adhesive Sample 2

[0068] 0.5 wt % of Epolight 1125, an NIR absorbing dye available fromEpolight, was dissolved homogeneously into the base hot melt adhesive(Cool-Lok 34-2125) and uniformly blended with the adhesive with a paddlemixer.

[0069] Adhesive Sample 3

[0070] An EVA based waterborne emulsion having the compositioncomprising 88.0 wt % EVA Emulsion (Dur-o-set E-200, Vinamul), 7.5 wt %Diethylene/Dipropylene Glycol Dibenzoate Plasticizer, 4 wt % water and0.5 wt % Carbon Black (Plack Pearls 4750, Cabot) was prepared bypre-dispersing the carbon black in the plasticizer using a rotor-stator.The the EVA emulsion and water were added using moderate speed axialpaddle stirring.

[0071] Many modifications and variations of this invention can be madewithout departing from its spirit and scope, as will be apparent tothose skilled in the art. The specific embodiments described herein areoffered by way of example only, and the invention is to be limited onlyby the terms of the appended claims, along with the full scope ofequivalents to which such claims are entitled.

1. A packaging machine comprising a means for reactivating an adhesivepresent on a packaging substrate, said means comprising a source ofultrasonic waves.
 2. The machine of claim 1 wherein said wherein saidreactivatable adhesive reactivates upon exposure to wave energy of fromabout 15 kiloHertz to about 60 kiloHertz.
 3. The machine of claim 2wherein said wherein said reactivatable adhesive reactivates uponexposure to wave energy of from about 20 kiloHertz to about 40kiloHertz.
 4. The machine of claim 2 wherein said reactivation means isan ultrasonic horn.
 5. The machine of claim 4 wherein said ultrasonichorn is a rectangular horn.
 6. The machine of claim 4 wherein saidultrasonic horn is a rotory horn or cylindrical shape.
 7. A process ofpackaging an article by forming, filling and sealing a package that hashad applied to at least a portion thereof a reactivatable adhesive, saidprocess comprising forming and/or sealing a package by exposing theapplied reactivatable adhesive to radiant energy for a time sufficientto reactivate the adhesive, said radiant energy being ultrasonic waves.8. The process of claim 7 wherein the applied adhesive activated bycontacting the substate with an ultrasonic horn.
 9. The process of claim8 wherein the ultrasonic horn is a rectangular horn.
 10. The process ofclaim 8 wherein the ultrasonic horn rotary horn of cylindrical shape.11. The process of claim 7 wherein said reactivatable adhesivereactivates upon exposure to wave energy of from about 15 kiloHertz toabout 60 kiloHertz.
 12. The process of claim 11 wherein saidreactivatable adhesive reactivates upon exposure to wave energy of fromabout 20 kiloHertz to about 40 kiloHertz.
 13. The process of claim 7wherein the package comprises vertical side panels, and at least a topand/or bottom flap.
 14. The process of claim 7, wherein said adhesive isapplied to at least one of said top or bottom flap.
 15. The process ofclaim 11, wherein said adhesive is applied to a vertical side panel. 16.The process of claim 7 wherein said package is a tubular shaped carton.17. The process of claim 7 wherein said package is a tubular shapedcase.
 18. A form, fill and seal packaging machine comprising a frame, aplurality of stations carried by the frame, and a feeding means forfeeding cartons to be formed, filled and sealed, said stationscomprising a carton erection station, a bottom and/or top flap sealingstation and a filling station, said top and/or bottom sealing stationcomprising a source of ultrasonic waves.
 19. The packaging machine ofclaim 18 wherein said reactivatable adhesive reactivates upon exposureto wave energy of from about 15 kiloHertz to about 60 kiloHertz.
 20. Themachine of claim 18 wherein said wherein said reactivatable adhesivereactivates upon exposure to wave energy of from about 20 kiloHertz toabout 40 kiloHertz.
 21. The packaging machine of claim 18 wherein thefilling station is located between the bottom flap sealing station andthe top flap sealing station.
 22. The packaging machine of claim 18wherein the source of ultrasonic waves is an ultrasonic horn.
 23. Anarticle of manufacture having applied on at least one substrate surfacethereof an adhesive capable of being reactivated upon exposure toultrasonic waves.
 24. The article of claim 23 which is a flat cartonblank.
 25. The carton blank of claim 24 wherein the adhesive is athermoplastic.
 26. The carton blank of claim 23 which is a flat, foldedcarton blank.